The FlexRAID recycle bin option is specific to Snapshot RAID and does not have an undelete feature as you would expect.
Do not delete anything you have not backed up unless you are sure you want it gone.
It might be safer to delete the configuration, regain control of your drives, and handle the duplicated data as appropriate; the FlexRAID recycle bin is not related to your OS recycle bin, which FlexRAID disables.
Essentially, once you delete something from the pool, it is gone forever.
The disable of the windows recycle bin is two fold I believe:
First, disable because flexraid does it differently with the pool.
Second, Delete anything so it's not there forever and can't be deleted later or gets duplicated. If using the FlexRAID storage pooling feature with the recycle bin feature turned on, your ONLY other risk are edits (changing the file’s content) as renames, moves, and deletes won’t be an issue.